Preventing an overloading of the electronic evaluation system due to voltage spikes in magneto-inductive flowmeters

ABSTRACT

The disclosure relates to a circuit arrangement for preventing overloading of magneto-inductive flowmeters. The disclosure can protect the amplifiers which are connected downstream thereof or the electronic evaluation system from overloading. To this end, the signal input circuit is provided with additional voltage-limiting diodes disposed downstream of the impedance converters so that eventual voltage tips are prevented during modulation in the downstream amplifiers of the evaluation electronics.

RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to German PatentApplication No. 10 2005 061 836.7 filed in Germany on Dec. 23, 2005 andGerman Patent Application No. 10 2006 007 394.0 filed in Germany on Feb.17, 2006, and as a continuation application under 35 U.S.C. §120 toPCT/EP2006/011991 filed as an International Application on Dec. 13, 2006designating the U.S., the entire contents of which are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

The disclosure relates to the known measuring principle used inmagneto-inductive flowmeters (MIF). For example, the disclosure relatesto an electronic circuit which allows interference voltage spikesU_(int), which can be additively superposed on the useful signals of thesignal voltage U₀, and thus lead to an overloading of the electronicevaluation system, to be eliminated.

BACKGROUND INFORMATION

If an electronic evaluation system is overloaded, then the measuredvalue cannot be determined during the overload. The current state of theart is to keep the measured value by means of downstream filterfunctions until interference-free signals are present once again. Adisadvantage of the aforementioned method is the increased response timeof the measuring system.

Signal voltage U ₀ =kvBD+U _(int)

SUMMARY

Exemplary embodiments disclosed herein can damp the interference spikesoccurring in the measurement procedure more strongly in order to protectthe downstream amplifier.

A circuit arrangement for preventing an overloading of magneto-inductiveflowmeters is disclosed, wherein the signal input circuit is providedwith additional voltage-limiting diodes downstream of the impedanceconverters in such a way that possible interference spikes are preventedfrom passing through to the downstream amplifier of the electronicevaluation system.

A circuit arrangement for preventing an overloading of magneto-inductiveflowmeters is disclosed, wherein the signal input circuit is providedwith additional semiconductor components and/or an amplifier circuitwith a low wattage downstream of the impedance converters so thatpossible interference spikes are prevented from passing through to thedownstream amplifier of the electronic evaluation system.

In another aspect, a method is disclosed for preventing an overloadingof magneto-inductive flowmeters based on a circuit arrangement. Themethod comprises providing a signal input circuit with voltage-limitingdiodes downstream of an impedance converters to prevent possibleinterference spikes from passing through to a downstream amplifier.

BRIEF DESCRIPTION OF THE DRAWING

An exemplary embodiment to eliminate interference spikes superposed onthe useful signal is illustrated. Specifically, a single FIGURE shows anexemplary electronic circuit diagram as described in the following text.

DETAILED DESCRIPTION

The disclosure relates to the known measuring principle used inmagneto-inductive flowmeters (MIF). The physical effect used to measurethe flow velocity is the law of induction. If an electrically conductivemeasuring material is lead through a magnetic field {right arrow over(B)}, an electric field {right arrow over (E)} which is perpendicular tothe flow direction {right arrow over (v)} and the direction of themagnetic field is generated in the measuring material.

The disclosure relates to an exemplary electronic circuit embodimentwhich allows interference voltage spikes U_(int), which can beadditively superposed on the useful signals of the signal voltage U₀,and thus lead to an overloading of the electronic evaluation system, tobe eliminated.

It is now the idea of the disclosure to connect additionalvoltage-limiting diodes 10 downstream of the impedance converters in thesignal input circuit 1 illustrated in the circuit diagram, in order toprevent passing possible interference spikes, and to protect thedownstream amplifiers of the electronic evaluation system fromoverloading.

It is known to operate impedance converters with an amplification of 1.The signal voltage needs to be amplified a number of times by thesubsequent amplifier stages of the electronic evaluation system in orderto evaluate the very small signal voltages. Interference spikes whichoccur are generally much greater than the signal voltage and can thuslead to an amplifier overload.

The illustrated exemplary circuit embodiment allows elimination of theinterference spikes from the amplifier stages, so that overloading, andthus interference, of the measurement operation cannot occur.

In an alternative exemplary embodiment, the voltage-limiting diodes aresimply exchanged for corresponding semiconductor components and/or anamplifier circuit with a decreased wattage.

It will be appreciated by those skilled in the art that the presentdisclosure can be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentlydisclosed embodiments are therefore considered in all respects to beillustrative and not restricted. The scope of the disclosure isindicated by the appended claims rather than the foregoing descriptionand all changes that come within the meaning and range and equivalencethereof are intended to be embraced therein.

1. A circuit arrangement for preventing an overloading ofmagneto-inductive flowmeters, wherein a signal input circuit is providedwith additional voltage-limiting diodes downstream of impedanceconverters in such a way that possible interference spikes are preventedfrom passing through to a downstream amplifier.
 2. A circuit arrangementfor preventing an overloading of magneto-inductive flowmeters, wherein asignal input circuit is provided with additional semiconductorcomponents and/or an amplifier circuit with a low wattage downstream ofimpedance converters so that possible interference spikes are preventedfrom passing through to a downstream amplifier.
 3. A method forpreventing an overloading of magneto-inductive flowmeters based on acircuit arrangement, the method comprising: Providing a signal inputcircuit with voltage-limiting diodes downstream of an impedanceconverters to prevent possible interference spikes from passing throughto a downstream amplifier.
 4. The circuit arrangement of claim 1,wherein the downstream amplifier is a part of an electronic evaluationsystem.
 5. The circuit arrangement of claim 2, wherein the downstreamamplifier is a part of an electronic evaluation system.
 6. The method ofclaim 3, wherein the downstream amplifier is a part of an electronicevaluation system.